Introduction: Seed amplification assays (SAAs) demonstrate remarkable diagnostic performance in alpha-synucleinopathies. However, existing protocols lack accessibility in routine laboratories, mainly due to the requirement for in-house production of recombinant alpha-synuclein (aSyn). This study proposes a cerebrospinal fluid (CSF) aSyn-SAA protocol using solely commercial reagents to facilitate its clinical implementation.
Methods: Routine clinical care CSF samples from 126 patients, comprising 47 with Lewy body diseases (LBD) (41 with dementia with Lewy bodies, six with Parkinson's disease), 37 without alpha-synucleinopathy, and 42 with Alzheimer's disease (AD), underwent assessment for aSyn-SAA activity.
Results: CSF aSyn-SAA showed a sensitivity of 72.3% and a specificity of 100% when distinguishing clinically diagnosed LBD patients from those without alpha-synucleinopathy. In AD patients, 14.3% were tested positive for aSyn.
Discussion: The commercial-only CSF aSyn-SAA protocol exhibited excellent specificity when applied to a real-life cohort, signaling progress toward the accessibility of an aSyn biomarker in clinical settings.
Highlights: Diagnosis of LBD through aSyn-SAA lacks accessibility.This commercial-only aSyn-SAA has satisfactory performance in a real-life cohort.A negative aSyn-SAA does not completely exclude a synucleinopathy.Some technical points must be considered when developing aSyn-SAA.aSyn-SAA must be confined to expert laboratories due to prion-like risk management.
Keywords: Lewy body disease (LBD); Parkinson's disease (PD); aSyn; alpha‐synuclein (α‐synuclein); biomarker; brain homogenate (BH); cerebrospinal fluid (CSF); dementia with Lewy bodies (DLB); neurodegenerative diseases; proteinopathies; real‐life cohort; real‐time quaking‐induced conversion (RT‐QuIC); seed amplification assay (SAA); synucleinopathies.
© 2025 The Author(s). Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals, LLC on behalf of Alzheimer's Association.